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What is syncope and black out ?

Definition of Syncope
          It is the sudden transient loss of consciousness and the patient is unable to maintain upright posture. It is due to impaired cerebral blood flow.
Causes of syncope
1. Simple syncope otherwise called vasovagal syncope occur due to vasovagal phenomenon. They are associated with unpleasant sight, cough syncope micturition syncope, carotid sinus syncope and acute severe pain.
2.    Cardiovascular syncope
Occur in cardiovascular disorders, common disorders associated are
-          Complete heart block
-          Sick sinus syndrome
-          Brady or tachyarrhythmia
-          Prolonged QT interval
-          Aortic stenosis
-          Eisenmenger syndrome
-          Hypertensive carotid sinus syncope
-          Acute pulmonary embolism.
3.    Postural hypotension is a cause of syncope occur in patients receiving drugs such as antihypertensives and vasodilators. Eg. are methyldopa, Prazoin and Diuretics
4.    Metabolic causes of syncope are hypoglycemia and alcohol intoxication.
5. Neurological causes of syncope are verebro baaclar insufficiency familial dysautonomic.
6.    Unknown causes.

Following are the causes of syncope with episodic fainting.
1.            Hyperventilation syndrome
2.            Transient ischemic attack
3.    Severe anemia
4.    Hypoglycaemia
5.    Acute blood loss

Important history to be taken in a patient with syncopal attack are
1.   Duration of attack
2.    Associated with exertion – Exertional syncope is seen with aortic stenosis.
3.    Convulsion present or absent
4.    History of repeated attack
5.    Preceding symptoms such as light headedness